This SBIR program will develop a disposable CO2 sensor for use in emergency resuscitation situations. The sensor will monitor the efficacy of such treatment in real-time. The sensor would connect to a small, non-disposable electronic readout. Existing instrumentation is a colorimetric paper that is large, can be used only for a limited time, and only gives a qualitative readout. The proposed device is very small and non-intrusive, can be used for an extended period of time, and would have a high accuracy quantitative readout. It could be adopted to replace larger, more expensive equipment now used in critical care areas. Sensor operating principals are based upon non-dispersive infrared spectroscopy. Using a reference signal to subtract effects of water droplets, dust, and other noise, the sensor can measure vapor concentrations to better than 10 parts per million accuracy. The light source and detector are fabricated by microelectromechanical systems technology, or MEMS, and can operate at high speed to measure concentration of CO2 versus time in a single breath. [unreadable] [unreadable]